1. Field of the Invention
The invention generally relates to the acquisition of IPv6 domain name system (DNS) and Session Initiation Protocol (SIP) server addresses, and more particularly, to the acquisition of IPv6 DNS and SIP server addresses in mobile communications devices.
2. Description of the Related Art
With the explosive growth of Internet applications, more and more devices, such as personal computers, workstations, laptop computers, smart phones, and various electric appliances, require IP addresses to communicate on the Internet. This leads to a problem where the number of the commonly adopted IP addresses provided by the Internet Protocol version 4 (IPv4) may be used up. In order to accommodate the fast growing needs for IP addresses, the Internet Protocol version 6 (IPv6) has been proposed by the Internet Engineering Task Force (IETF) to solve the long-anticipated problem of IPv4 address exhaustion, and provide sufficient address space, a simplified header format, support for authentication and privacy, auto-configuration of address assignments, and new Quality-of-Service (QoS) capabilities. The IPv4 uses 32 bits for an IP address and therefore has 232 possible addresses, while the IPv6 uses 128 bits for an address and therefore has 2128 possible addresses (approximately 340 undecillion or 3.4×1038). This expansion can accommodate much more devices and users on the Internet and offer extra flexibility in allocating addresses and efficiency in routing traffic. This also relieves the need on Network Address Translation (NAT), which is widely deployed as a work around for the IPv4 address exhaustion problem. An IPv6 address is typically composed of two parts: a 64-bit network prefix (referred to herein as prefix for brevity) used for routing, and a 64-bit interface identifier used to identify a host's network interface. In general, the prefix is contained in the most significant 64 bits of the IPv6 address. The interface identifier is generated from the interface's MAC address using the modified Extended Unique Identifier -64 (EUI-64) format, assigned by the GERAN/UTRAN (GSM EDGE Radio Access Network/Universal Terrestrial Radio Access Network) Gateway GPRS Support Node(GGSN), assigned by the E-UTRAN (Evolved UTRAN) PDN Gateway (PGW), established randomly, or just assigned manually. Particularly, a dynamic IPv6 address is configured using the stateless address auto-configuration (SLAAC).
However, the Terminal Equipment (TE) may get the IPv6 address but not acquire the IPv6 DNS and/or SIP server address because the O-flag in Router Advertisement (RA) may not be set or there may not be a proper protocol to acquire the IPv6 DNS and/or SIP server address from the Mobile Terminal (MT). As a result, the Terminal Equipment (TE) may not obtain the required IPv6 DNS server address in time for analyzing the domain name and/or IPv6 SIP server address for session registration to enable VoIP or IMS service.